The Philosophical Problem of Skepticism

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I. The Problem

A. The following claims are individually plausible but jointly inconsistent:

1. Certainty Principle: Knowledge requires evidence that is sufficient to rule out the possibility of error.

2. Content Internalism: The way things seem can be very different from the way things really are.

3. Phenomenalism: We are directly aware only of appearances not of reality.

4. Common Sense Epistemology: We know a great deal about the external world.

B. Proof of the joint inconsistency of the above claims:

P1: S knows some proposition P about the external world only if S can rule out the possibility that she is mistaken about P.

[from, Certainty Principle]

P2: S cannot rule out the possibility that she is mistaken about P.

2a: S’s evidence concerning P is limited to the way things

seem regarding P. [from, Phenomenalism]

2b: The way things seem regarding P can be very different from the way things really are. [from, Content Internalism]

C: So, S does not know P. [contra, Common Sense Epistemology]

II. Responses

A. Skepticism:

1. We do not know many of the propositions about the external world that we naturally take ourselves to know.

2. Rejects Common Sense Epistemology

B. Epistemic Externalism

1. Knowledge does not require that an epistemic agent have access to evidence, only that one’s beliefs be in fact reliably virtuously produced.

2. Rejects the Certainty Principle

C. Direct Realism

1. We have in sense perception direct access to external world objects.

2. Rejects Phenomenalism

D. Content Externalism

1. Which thoughts we can think is determined in part by the external environment to which we are related.

2. Rejects Content Internalism

E. Contextualism

1. The standards for knowledge vary with context, from relatively low common sense standards to relatively high philosophical standards.

2. Rejects Certainty Principle in common sense contexts.

3. Rejects Common Sense Epistemology in philosophical contexts.